1. Field of the Invention
The present invention relates to switchgear apparatus that have a pair of electrodes that are able to make/break a contact therebetween, and perform open/close operations of the pair of electrodes by contacting or separating the electrodes each other, in particular, to the switchgear apparatus that are electromagnetically driven.
2. Description of the Related Art
A conventional switchgear using an electromagnetic force is constituted of a movable electrode and a fixed electrode, and further constituted of a switching unit that directly performs so as to open/close an electric circuit; a movable shaft that is extended from the movable electrode; and an operating mechanism that is driven by a power source, and opens/closes the switching unit by providing the driving force onto the movable shaft.
In such a switchgear, because the driving force originating from the electromagnetic force is utilized therein, the open/close operations tend to be performed in a high speed. Particularly in the close operation, a large striking force is produced when the movable electrode collides against the fixed electrode; because of the impact, a repetitive contact phenomenon between the electrodes (hereinafter referred to as “chattering”) is generated. When a duration of the chattering or “chattering time” is long, there can be raised a problem in which the electrodes may be welded to each other; therefore, it is necessary to shorten the chattering time as much as possible. For this reason, for example, there exits a proposal in which two open/close units (interrupters) are placed in series to oppose each other and, at the same time, the fixed-side electrodes are back-to-back connected to each other and fixed; thus, by counterbalancing or canceling the striking force produced when the movable electrodes collide against the respective fixed electrodes, damage to a supporting member that supports both the fixed electrodes is prevented; concurrently, an electric circuit including the switches each in two open/close units is so arranged as to be interrupted easily and reliably (for example, refer to Japanese Patent Application Publication No. 2002-124157).
In addition, there exits another proposal in which a decelerating means (a set of dampers) is provided in an operating mechanism that opens/closes a switching unit so as to mitigate the impact caused by the open/close operations, so that the striking force is mitigated, and high-speed responsivity of the open/close operations is secured (for example, refer to Japanese Patent Application Publication No. 2002-124165).
As for a switchgear in Japanese Patent Application Publication No. 2002-124157, because two open/close units are placed in series, it is difficult to place the units without providing sufficient space therefor.
In addition, as for a switchgear in Japanese Patent Application Publication No. 2002-124165, because a configuration is taken in which expensive dampers are placed so that energy due to the impact is dampened, product costs tend to become high, which has hitherto caused a problem.
The present invention has been directed at solving those problems in conventional technologies described above, and an object of the invention is to provide switchgear apparatus that have high reliability with low costs, and are compact (space saving).